OFFICE OF SCIENCE
Dark Matter at the DOE Cosmic Frontier
AMS Days at CERN April 15-17, 2015
Michael Salamon Office of High Energy Physics Office of Science, U.S. Department of Energy
1 OFFICE OF SCIENCE
Where Dark Matter resides in DOE
2 3 4
5 Cosmic Frontier Program
• Studies of the nature of Dark Energy using imaging and spectroscopic surveys • Direct detection searches for Dark Matter particles • Study of the high energy universe and indirect dark matter searches using Cosmic-ray, Gamma-ray experiments • CMB experiments to study the nature of inflation, neutrino properties, and dark energy • Other efforts, including • Computational cosmology efforts • Other experiments
FY 2016 High Energy Physics Budget
HEP Funding Category FY 2014 FY 2015 FY 2016 ($ in K) Current Enacted Request Explanation of Changes (FY16 vs. FY15) LHC detector upgrade fabrication; R&D for Energy Frontier 152,386 147,584 154,555 high-luminosity LHC upgrades Operations and upgrade of NuMI for NOvA Intensity Frontier 250,987 264,224 247,196 and MicroBooNE; R&D for LBNF and SBN Planned ramp-up of LSSTcam; support of DESI Cosmic Frontier 96,927 106,870 119,325 and 2nd generation dark matter experiments Planned increase in Lattice QCD project; slight Theoretical and Comp. 64,275 59,274 60,317 reduction in theory research efforts Reductions reflect shift to P5 priority areas; Advanced Technology R&D 150,270 120,254 115,369 MAP reduction continues in response to P5 Increase supports new research topic areas Accelerator Stewardship 9,075 10,000 14,000 and expands open test facility efforts Planned profile for Mu2e; engineering and Construction (Line Item) 51,000 37,000 56,100 design for LBNF SBIR/STTR 21,601* 20,794 21,138 Total• adf 796,521* 766,000 788,000
* SBIR/STTR added to FY 2014 7 for comparison to FY 2015/2016 Dark Matter Program within the Cosmic Frontier
(NAS Board of Physics and Astronomy report, 2011)
8 Evidence for Dark Matter
Weak lensing Galactic (Bullet Cluster) rotation But what is it? And how do we search for it?
Planck power spectrum
Courtesy of Dan Bauer
9 WIMP Dark Matter Complementarity
Courtesy of Joanne Hewett and collaborators 10 Complementary Techniques for DM Detection
Indirect detection Direct detection
Collider production
11 Dark Matter Projects in the Cosmic Frontier
– Indirect Detection • Alpha Magnetic Spectrometer, in low Earth orbit • Fermi Gamma-ray Space Telescope (FGST), in low Earth orbit • High Altitude Water Čerenkov array (HAWC), in Mexico • VERITAS, in Arizona – First-Generation (G1) Direct Detection • WIMPs – DarkSide-50: LAr TPC, in Gran Sasso – LUX: LXe TPC, in Sanford Underground Research Facility (SURF)
– PICO: bubble chamber, 60 kg C3F8 target, in SNOLAB – SuperCDMS-Soudan: Cryo Ge crystals, in Soudan Mine • Axions – ADMX-IIa at the U. of Washington – Second-Generation (G2) Direct Detection (>10x sensitivity than G1) • WIMPs – LUX-Zepplin (LZ): 7-tonne LXe TPC in SURF – SuperCDMS-SNOLAB: Cryo Ge and Si in SNOLAB • Axions – ADMX-Gen2 at the U. of Washington
12 Complementary Techniques: pMSSM parameter space
Direct detection Indirect detection
Collider production
From Cahill- Rowley et al., arXiv:1405.6716 (May 2014)
13 Direct Detection of WIMPS • Virialized WIMPs Direct Detection of WIMPs low recoil energy need low backgroundsdeep underground labs
• low Qcoherent scattering (spin independent)
• need multiple targets to break degeneracies
Thanks to M. Attisha Direct Detection: the WIMP Neutrino Floor
Courtesy of SuperCDMS Collab
15 DarkSide-50 (G1)
Dark Matter Search with 2-phase, liquid argon TPC as target (45kg) at LNGS Sensitivity goal 2 x 10-45 cm2 • low-radioactivity argon from underground (Co., U.S.A) (UAr) • borated liquid scintillator veto • water cerenkov veto
16 DarkSide-50
China France Italy Poland
Russia Ukraine U.S.A. 7 nations, 32 institutions
arXiv:1501.03541v1 (Jan 2015) Discrimination: • Singlet to triplet scintillation ratio • Electromagnetic recoil vs. nuclear recoil ionization yield • Fiducial cuts with TPC.
17 LZ (LUX-ZEPPLIN) (G2)
• LXe TPC detector • Coherent WIMP scattering scales as ~A2, giving Xe an advantage in sensitivity reach • Located at the Sanford Underground Research Facility (SURF) in South Dakota, USA • G1 version (LUX), 250 kg LXe active mass is now in middle of 300-day run. Generation 2 experiment • 10 total tonnes of LXe, 7 active tonnes with extensive background veto systems to maximize useful mass • U.S. – UK – Portugal – Russia • Currently 29 institutions and 160 people, continuing to grow • Start operation 2019
18 LZ Spin Independent Sensitivity for 1,000 Days
• LUX (2013) limit from 1000 kg-day operation (arXiv 1310.8214) • LUX-300 day result in 2016, after which operations cease in preparation for LZ. • LZ result with 1000 days livetime PICO (PICASSO + COUPP): Bubble Chamber DM Search (G1)
• Superheated fluid in bubble chamber.
• Energy deposition > Eth in radius < rc from particle interaction will result in expanding bubble. A smaller or more diffuse energy deposit will not. • Thermodynamic parameters are chosen for sensitivity to nuclear recoils but not to electron recoils. • Better than 10-10 reject of electron recoils (β and Υ)!
• PICO collaboration operates two bubble chambers at
SNOLAB: PICO-2L (2 liters C3F8 target) and PICO-60 (20 liters CF3I target in 2013-2014 Run). • Comparison of rates on different targets allows unique tests of signal, background models. • Thermodynamic conditions tuned to reject backgrounds according to specific energy loss (dE/dX). • Acoustic signals from bubble growth provide additional background discrimination.
20 PICO 2015 Results (Preliminary)
• Competitive sensitivity for both spin-dependent Collaboration: and independent WIMP couplings. • 5 nations: Canada, Czech • Leading experiment for WIMP-proton spin Republic, India, Spain, U.S.A. dependent sensitivity: ArXiv:1503.0008. • 15 institutions • Transition from CF3I target liquid to C3F8 extends sensitivity to lower masses.
Spin-dependent Spin-Independent DAMA PICASSO COGENT CDMS-SI
PICO-2L 2015 SuperCDMS (Cryogenic Dark Matter Search)
Standard CDMS mode for DM detection: • Cryogenic Ge detectors operating at ~15 mK • WIMP interaction creates phonons and electron-hole pairs • Phonons measured with transition edge sensors • Ionization charge drifts to amplifiers • Charge/phonon ratio discriminates against electron recoil
HV mode: Luke-Neganov phonon amplification: • Increase voltage, phonons produced by drifting pairs dominate phonon signal •Ability to count at the few electron charge level, allows for detection at 22 SuperCDMS-Soudan (G1) + SNOLAB (G2) arXiv: 1402.7137v2 (Mar 2014) ] 2 DM SuperCDMS-Soudan - nucleoncross section[ • 15 Ge crystal detectors, 0.6kg each Super • operating in the Soudan Underground CDMS Lab since 2012 • Published limits on WIMPs, axions, lightly ionizing matter • operations coming to end to prepare for nucleon cross section [cm section cross nucleon - pb G2 version, SuperCDMS-SNOLAB ] DM • latest (March 2014) limits from 557 kg- Dark-matter mass [GeV/c2] days exposure. SuperCDMS-SNOLAB • G2 version of SuperCDMS; to be located in SNOLAB (greater depth than Soudan) • Both Ge and Si cryogenic crystals, Si for very low WIMP mass sensitivity • Both standard and HV modes implemented; dedicated crystals for each mode. • In potential partnership with Europe’s EURECA collaboration, may have up to ~200 kg of Ge, smaller amount of Si. • Canada, Spain, UK, US (+ France, Germany from EURECA) arXiv:1309.3259v3 (Dec 2013) 23 SuperCDMS-SNOLAB Expected Sensitivity Reach Courtesy of SuperCDMS Collab ADMX (Axion Dark Matter Experiment) (G2) • Search for dark-matter axions; viable DM mass range is ~μeV to meV. • Peccei-Quinn axion-photon coupling defines target sensitivity. • Strong magnetic field in resonant cavity converts axions (from the dark matter Galactic halo) into photons via the Primakoff effect. • Detector consists of a dilution-fridge cooled microwave cavity in a large superconducting 8 Tesla magnet. Microwave photons detected by an ultra- low-noise SQUID-based microwave .amplifier/receiver. These provide the sensitivity • ADMX is sensitive to sub-yoctowatts of microwave power. • 23 scientists from 2 countries. 4m ADMX has the sensitivity to either detect the dark-matter QCD axion or reject the hypothesis at high confidence. This is called the “Definitive Search”. 25 ADMX-Gen2 Expected Sensitivity 26 Indirect Detection of WIMP Dark Matter ρ(r) r ρ(r) = DM radial density DM ball = Dwarf spheroidal galaxy e+ Local Galactic halo 27 VERITAS Very Energetic Radiation Imaging Telescope Array • Imaging air Čerenkov telescope array in Arizona, pioneered by Trevor Weekes • 50 GeV-50 TeV gamma-ray energy range • complements FGST energy arXiv:1202.2144 range •Deep observation of DM-rich dwarf • Canada, Germany, Ireland, US: spheroidal galaxy Segue 1 ~100 scientist • • 4 telescope operation started in ~2 orders of magnitude above the -36 3 2007; continuing operation. relic <σv> of ~3 x 10 cm /s 28 Fermi Gamma-ray Space Telescope Science Goals • Study high-energy (~20 MeV->300 GeV) g rays using particle physics detector technology in space • Indirect dark matter detection; high-energy acceleration mechanisms Partnership • DOE, NASA and 6 international agencies partnered on construction of the Large Area Telescope (LAT) on Fermi; NASA leads the mission, DOE supports LAT Instrument Science Operations Center at SLAC Instrument • Pair conversion telescope with tracker and calorimeter • Field of view = 2.4 sr • Effective area = 0.95 m2 • Point source sensitivity ~ 3 x 10-9 cm-2s-1 • Launched June 2008 29 FGST limits on relic <σv> Dwarf spheriodal galaxies: nearly pure balls of DM orbiting Milky Way Combined DES dSph candidates Combined known dSphs (Ackermann et al., arXiv:1503.02641) “Search for Gamma-ray Emission from DES Dwarf Spheroidal Galaxy Candidates with Fermi-LAT Data” (March 2015) arXiv:1503.02632v2 (Fermi-LAT and DES Collaborations) 30 HAWC (High Altitude Water Čerenkov array) Sky survey of ~100 GeV to >100 TeV gamma-rays •Air Shower Detector with 300 Water Cherenkov Detector tanks covering 20,000 m2 at 4100 m on Sierra Negra Volcano, Mexico. Exposure to half of the sky during a 24-hour period. Final tank was filled in January 2015. Science Goals • Indirect dark matter search for gamma-rays from WIMP annihilation. • Other astrophysical sources, e.g., supermassive black holes in active galactic nuclei and gamma ray bursts. ~100 scientists from US and Mexico. LANL, NASA/GSFC, 15 US universities, 11 Mexican institutions 31 HAWC performance Because the flux of gamma rays from all sources drops rapidly as a function of energy, observations of sources require a large effective area and long integration times, especially if the goal is to observe gamma rays above 10 TeV. Specifications: • Large FOV: out to 45o from zenith • Duty cycle: >90% (insensitive to Sun or Moon) • 1-year point source sensitivity (>2 TeV) ~ 3 x 10-13 cm-2s-1 Reference -- arXiv:1405.1730 32 The Alpha Magnetic Spectrometer 33 Selected Elements of AMS History • 1994: – AMS concept development begins – Prof. Ting visits the NASA Administrator, (Dan Golden) to explore NASA interest in AMS – AMS first proposed to DOE • April 1995: first DOE-AMS Committee Review (“Blue Ribbon Panel”) • 1997: AMS becomes a “recognized experiment” at CERN • June 1998: AMS-01 “engineering test” Space Shuttle flight • March 1999: second DOE-AMS Committee Review • September 2006: third DOE-AMS Committee Review • January 2010: NASA-DOE Implementing Arrangement signed: NASA delivers payload, provides ISS services; DOE responsible U.S. science effort. • May 2011: AMS-02 arrives at ISS, is installed, taking data within 5 hours • September 2013: fourth and most recent DOE-AMS Committee Review – Chair report endorses continued operation onboard the ISS at least to 2020, at which point statistical errors will be have been halved. – Next DOE-AMS Committee Review expected to be held in 2016-201 34 Great interest in AMS physics • 1st paper (5 Apr 2013) - selected for VIEWPOINT in Physics. Also an Annual Highlight of 2013. “First Result from the Alpha Magnetic Spectrometer on the International Space Station: Precision Measurement of the Positron Fraction in Primary Cosmic Rays of 0.5–350 GeV,” Phys. Rev. Lett. 110, 141102. • 2nd paper (19 Sep 2014) - selected as Editor’s suggestion. “High Statistics Measurement of the Positron Fraction in Primary Cosmic Rays of 0.5–500 GeV with the Alpha Magnetic Spectrometer on the International Space Station,” Phys. Rev. Lett. 113, 121101. • 3rd paper (19 Sep 2014) - selected as Editor’s suggestion. “Electron and Positron Fluxes in Primary Cosmic Rays Measured with the Alpha Magnetic Spectrometer on the International Space Station,” Phys. Rev. Lett. 113, 121102. • 4th paper (28 Nov. 2014) “Precision Measurement of the (e+ + e−) Flux in Primary Cosmic Rays from 0.5 GeV to 1 TeV with the Alpha Magnetic Spectrometer on the International Space Station,” Phys. Rev. Lett. 113, 221102. • 5th paper (coming soon) - selected as Editor’s suggestion. “Precision Measurement of the Proton Flux in Primary Cosmic Rays from Rigidity 1 GV to 1.8 TV with the Alpha Magnetic Spectrometer on the International Space Station,” Phys. Rev. Lett. • This conference! (My thanks to Mike Capell) 35 Example: the AMS Cosmic Ray Positron Fraction AMS-02 has provided us with unprecedented precision and accuracy in the measurement of cosmic rays. These data are revolutionizing the field of cosmic ray physics. They already provide hints of new physics. ? “AMS is a particle physics experiment in space.” Uniquely capable, its discovery space is large. History tells us that new phenomena are revealed when L. Accardo et al., Phys. Rev. Lett. new frontiers are opened. 113, 121101 (2014) 36 Final Words on AMS AMS is the product of a superb international collaboration. It is a poster child not only for “global physics,” but also for collaboration in the U.S. between DOE and NASA. “AMS is a new space telescope, observing the cosmos not through photons but through charged particles. come from opening new frontiers to scientific investigation.” Anonymous reviewer from the 2013 DOE AMS Committee Review 37 Summary DOE’s Cosmic Frontier has a vital and comprehensive program in dark matter research: • First generation WIMP direct detection experiments: several different target media and detection techniques • Second generation WIMP direct detection experiments: multiple (two) target media, cover WIMP mass range of ~100 to 103 GeV, get close to the irreducible neutrino background. • Indirect detection projects, both space-based and ground-based observatories, place limits on thermal relic cross section. • Second generation axion detector, will provide definitive answer to whether PQ axions constitute the DM over most of the viable DM axion mass range • DM R&D will continue to develop technologies for potential international G3 experiment. 38 BACKUP 39 Particle Physics Project Prioritization Panel (P5) The two U.S. high energy physics funding agencies, DOE/HEP and NSF/Physics, need a compelling & executable strategic plan, with full community support behind it. • APS-DPF led a community planning process in 2013 (“Snowmass”) • HEPAP P5 Subpanel in 2013/2014 (Steve Ritz, Chair) used Snowmass and other inputs to develop a strategic plan for the field • Plan to be executed over a ten year timescale in the context of a 20- year global vision for the field • P5 process was carried out in the context of realistic budget scenarios provided by the funding agencies in the charge The P5 report “Strategic Plan for US Particle Physics in the Global Context” was delivered and approved by HEPAP in May 2014. This report has been exceptionally well received in all parts of the U.S. Government Large community buy-in has been a very important factor. 40 Cosmic Frontier Strategy P5 strategic plan: 5 science drivers P5 report recommendations addressed several thrust areas of the Cosmic Frontier: • Dark Energy – Build DESI as a major step forward in dark energy science – Complete LSST as planned • Dark Matter – Proceed immediately with a broad second-generation (G2) dark matter direct detection program with at least two detector media, with WIMP mass range 1 GeV to 100 TeV. • Invest in this program at a level significantly above that called for in the 2012 joint agency announcement of opportunity – Support one or more third-generation (G3) direct detection experiments • Guide G3 by the results of the preceding (G1, G2) searches • Seek a globally complementary program and increased international partnership in G3 experiments • Cosmic Microwave Background (CMB) – Support CMB experiments as part of the core particle physics program – The multidisciplinary nature of the science warrants continued multiagency support • Cosmic Rays and Gamma Rays – Invest in CTA only if the critical NSF Astronomy funding can be obtained 41